| name | recon-js-analysis |
| description | Mine JavaScript for endpoints, params, secrets, and hidden functionality. Load on SPAs, heavy JS apps, after crawling, or "analyze the JS". Signals: bundled JS (webpack/main.*.js), API calls in JS, source maps, /static/js, front-end frameworks.
|
| domain | recon |
| type | technique |
| stability | learning |
| modes | ["bugbounty"] |
| severity | medium |
| mitre | ["T1592.002"] |
| tools | ["katana","linkfinder","jsluice","subjs","source-map-explorer"] |
| schema_version | 1 |
JavaScript analysis
When it applies
The app is JS-heavy (SPA). The front-end bundle is a map of the backend: it references API
endpoints, parameters, feature flags, roles, and sometimes secrets — much of it not linked in the UI.
Why it works
Client code must know how to call the server, so endpoints/params are embedded in JS. Bundlers
also occasionally ship source maps (full original source) and developers leave keys/comments.
Method
- Collect all JS:
katana -jc, subjs, or crawl; grab every .js (incl. lazy-loaded chunks).
- Extract endpoints/params:
linkfinder/jsluice pull URLs, paths, and param names from bundles.
- Hunt secrets & flags: grep for
apiKey|token|secret|internal|admin|debug, feature flags,
and role checks done client-side (server may not enforce them → BOLA/BFLA leads).
- Source maps: if
.map files ship, reconstruct original source (source-map tools) → full whitebox-ish view.
- Feed results: new endpoints →
api-*; client-only auth checks → api-bola; secrets → validate.
Gotchas
- Client-side "admin" gating usually isn't enforced server-side — test the endpoints directly.
- De-obfuscate/beautify minified bundles before grepping (
js-beautify).
- Lazy-loaded chunks hide the juicy routes — enumerate all chunk files, not just
main.js.
Verify success
Endpoints/params/secrets extracted from JS that weren't in the UI — new, testable surface.
References
LinkFinder/jsluice; katana; "JS recon" bug-bounty methodology.
